score = float(input("请输入成绩："))

if score >= 90 :
    print(f"当前同学成绩为{score},等级为优")
elif score>=80 and score<90:
    print(f"当前同学成绩为{score},等级为良")
elif   70 <= score < 80:
    print(f"当前同学成绩为{score},等级为中")
elif   60 <= score < 70:
    print(f"当前同学成绩为{score},等级为合格")
else:
    print(f"当前同学成绩为{score},等级为不合格")